Without more information on what the animation is going to look like it is hard to say, however, I personally would only have one “root” bone between the girl’s feet on the floor, as is the case with a Rigify rig. I am guessing that the balloon is somewhere over her head and that the ballon has some influence on the girl’s movements? If so then the bones for the balloon, maybe only one is necessary, could be added to the girl’s Rigify rig.
You then have the option to move the Rigify “root” bone and therefore move the whole lot or you can add drivers or some constraints to the root bone or indeed the IK target bones that have the balloon bone as a target object. You can even have a separate “control” bone that has effect on both the root and balloon bones, the possibilities are quite long… I am off to your wonderful country tomorrow at 05:00 - merde! I thought there was only one 5 o’clock in the day - so I cannot really do any more to help until I get home in a week’s time’s. I am not taking my Mac with me - Mme. Clockmender would go nuts if I did!
So have a play and hopefully others will take up the challenge of helping. What would be really useful is a few sketches of the movements needed, like a storyboard, you can draw these on paper then scan them to your computer and upload them here. Also post an image of your model for us to look at. At some stage we may ask to see the blend file, in which case you can post it to pasteall.org/blend then post the link here. You cannot post blend files until you come off moderation I believe and then there is a 2Mb limit I think…
As you are new to BA I should have said “Bienvenue en BA” first and also if you don’t know how to post images, just click the “Go Advanced” button on a post, then find the “Manage Attachments” button and click that - a new window pops up and you can then choose an image (up to 3 in a post) and click “Upload” once done and the image appears in the lower row, put the cursor where you want the image in your post and click “Insert…”. You will be on moderation for 10 post, so expect delays before they appear, you can reduce the time it takes to make 10 posts by making meaningful posts on threads in the WIP for example.